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Old 01-23-2022, 09:36 PM   #4
GTO_Gregory
 
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Drives: 2016 Camaro
Join Date: Oct 2017
Location: Texas & Uncle Sam's Choice
Posts: 103
I'm not exactly why I had to use a vacuum pump, but I'm glad I did.
My LS2-402 seemed to have ring blow-by that elevated crankcase pressure.
I believe the blow-by existed because the 402 used the 6.0-liter block with shorter cylinder sleeves due to the shorter 3.62 0" stroke. The 4.000" stroke crankshaft caused the pistons to rock a tiny bit at the bottom of the stroke. The tiny bit of rock allowed blowby. The higher 13.0:1 compression compounded things.

Typically, though it seems higher compression race motors use vacuum pumps.
My combination made 554HP at tire on 93-octane.
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2006 Quicksilver 6-speed GTO ERL LS3-430, All-Pro 285cc heads, 262/273 .758/.742 116+3 cam, Sheet-metal Intake, 70lb Siemens injectors, SLP, GMM Ripshifter, QA1 Coil-overs front and rear, nylon suspension bushings, Hotchkis, RPM Trans, SPEC twin clutch, SpinTech, Kooks 1 7/8 -2.0", BMR drive train, Kaaz 3.91, Lingenfelter CAI, Baer brakes, mini-tubs, E85.
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